1. Field of the Invention
The present invention relates to a manufacturing method of a multilayer substrate, more particularly, to a manufacturing method of a multilayer substrate enabling improvement of positioning accuracy of wiring layers.
2. Description of the Related Art
With the development of high-performance and compact electronic equipment, multilayer wiring structures are more increasingly used in the mounting substrate housed inside electronic equipment. A conventional manufacturing method of a multilayer wiring substrate is hereinafter described with reference to FIG. 9.
First, a first conductive foil 101A and a second conductive foil 101B are attached to a front surface and respectively, to a rear surface of a substrate 100 comprising insulating material such as resin, etc., as illustrated in FIG. 9A.
Next, a process of selectively etching the first conductive foil 101A and the second conductive foil 101B is carried out to form a first wiring layer 102A and a second wiring layer 102B, as shown in FIG. 9B. The wiring layers are laminated via an insulating layer 103A so that a multilayer wiring structure shown in FIG. 9C is obtained. Here, an interconnecting portion 104 is a region for electrically connecting wiring layers.
In the above-described method, deviations in the positioning of the wiring layers occur and it is difficult to form an interconnecting portion 104 connecting similar layers with a high degree of accuracy. Nowadays, demands for compact and high-performance devices are steadily increasing, patterns become increasingly minute requiring accurate interconnection portions connecting layers and accurate positioning of the wiring layers.